Conventional chargers rely on an electrical, mechanical or digital signal technique to determine the type of battery being charged and thus the appropriate charge regime to apply. For example, some techniques are based on the use of an internal battery ID resistor, the value of which determines the charging parameters applied for that specific battery. Mechanical techniques have also been used, such as using the location of a connector polarity key or the location of a particular connector pin to distinguish between different battery models requiring different charging parameters. The Smart Battery SMBus standards, for example, use a serial data communications interface to communicate the charging parameters to the charging device. The above approaches require added connection points beyond the battery power terminals or some added mechanical feature not required for the basic battery function of delivering stored energy to a portable device. In the case of the Smart Battery standards, for example the SMBus standard, an electrical circuit and at least two additional connector pins are required to implement the smart interface between the charger and battery, adding to the cost, complexity and size of the battery.